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Arne? iris-@1 Patented 4, 1931 re uses RENE GLAVEL, 9F BASEL,SWITZERLAEQ'D WEIGHTING NATURAL SILK fie brewing. Application fil ed May16, 1927, Serial No. 191,941, and in Germany September 17, 3.928.

This invention relates to a method of weighting natural silkwithmetallic compounds.

Hitherto, in processes for weighting silk,

ii a number of substances have been brought m and neutralized.

temperature for rather a long time, say for about an hour or two, andthen thoroughly washed with water, in order to hydrolize the tin-saltson the fibre! lhe precipitated stannic acid is then fixed by treatingthe silk with a solution of di-sodium phosphate of about 6 per cent.strength, at a tempera ture of about 60 G. The tin-salts and phosphatetreatments are repeated alternately until the desired weighting has beenobtained, and after each bath the silk must undergo a thorough washingorneutralization. fAiter the last phosphate bath the silk may be treatedwith a solution of sulphate of alumina, and, after subsequent washing,with a solution oi water glass at a temperature of about 50 C. The silkwhich has been treated in this manner, and weighted with complexcompounds of tin, phosphate and water glass,

' is then washed with soap, rinsed and soured.

The method oi weightin which is described above, as well as :ot ormethods of wei 'htingwith various substances, wastes rnuc time, onaccount of the number of baths, and the washing, acidification orneutralization which is necessary between each bath. Such methods arealso very expensive, and their disadvantages are not to be overccruebythe use of the modern weighting centrifuges. The greatest of thesedisadvantages 1s theserious loss of material which is caused by the manywashing and neutralization processes, and the troublesome and expensiveprocesses which are necessary for the recovery of the weightingsubstances from the waste liquors.

According to the invention the weighting ofnatural silk is considerablysimplified and less expensive, when care is taken that the metal saltscome in contact with thesilk only at a certain high acid concentrationor in other words that the metal salts are acting upon the silk only inthepresence of acids or acid salts. The acids or acid salts necessaryfor obtaining the high acid concentration may be added to the metal saltbath for example a tin tetrachloride solution or the silk may be treatedwith acids or acid salts before taking it into the metal salt bath. Thenatural silk treated in such a manner with metal salts may then bebrought without previous washing-i1 desired after squeezing for removaloi the excess of tin tetrachloride solution into the following phosphatebath. .Due to the high acid concentration present during the metal salttreatment, the silk undergoes a change and the tin chloride probablyforms a compound with the silk, in which it is hydrolized. However, inno .case undesired precipitations take place in the phosphate bath andthe tin salt on the fibre combines with the phosphate into atin-phosphate compound, probably Sn (HPOQQ, adapted and necessary forwei 'hting sil when treating silk with a tin chloride solution withoutthe-presence of acids or acid salts it is not possible to bring the silktreated with the metal salts into the following phosphate bath withoutprevious washing of the silk, to hydrolize the tin chloride; There wouldoccur in the phosphate bath and upon the silk precipitations of tinsalts which are not adapted for weighting purposes, make the silkturbid, cloudy and milky and produce spots. with the invention tin saltbathswith increased acid concentration, undesired precipitations do notoccur, the silk is abundantly weighed, looks unobjectionable, and showsno s ots.

111 order to prevent the silk from being attacked too much by theincreased acid concentration it is advisable to use rotective holloidssuch as glue, gelatine, al umin or the like. These protective colloidsmay be If one uses, however, in accordance brought upon the silk eitherbefore bringingit into the acid tin salt solution for example by coatingor impregnation if desired together with the, acid substances, forexample acids, ormay be added to the tin salt bath.

it is also possible to treat the silk before bringing it into the metalsalt bath with acid substances such as acids or acid salts and to ke'thispretreatment in presence of protective colloids. The acidconcentration may then be kept lower in the metal salt bath or theaddition of acids or acid salts may be renounced. Also in these cases achange of the.

silk fibres takes place, which produces a more intensive and more equaltaking up of the weighting means. 1 Experiments show the surprisingfact, that silks of difi'erent origin took up equal amounts of weightingsubstances. The weighting of the silk is then carried through by passingthe silkthrough one or only a few weighting baths, in which the skeinsor textures only had to remain a and unsuitabletin compounds take place,be-

cause theba'th has an increased acid cone-en tration. In this case it isadvisable to use instead of phosphates, phosphoric acid, which serves adouble purpose namely to produce the tin-phosphate cqmpound and toincrease the acid concentration. Here too the addition of protectivecolloids is advisable, be

cause they do not only protect the silk but also help in-preventing theprecipltation of unsuitable tin compounds. It is even possible toaddsolutions or" water glass, which is a'substance used in the tinweighting proc ess to the weighting bath containing tin salt 7 andphosphate at increased acid concentration, thus carrying the entireweighting process through with a single bath.

if one treats the silk with weighting baths according to the presentinvention, using 7 proper concentration of the bath and a suitabletemperature, the silk is sulhciently weighted after only a very shorttreatment. The precipitation reactions which are necessary for perfectweighting and cannot occur in the bath on account or" the high acidconcentration, or the presence of the protective colloids, if desired athigh acid concentration, occur on the fibre immediately. It is therefore possible to produce weightings, which are-satisfactory and of goodquality by a simple application of the solution, such as by remote forexample of a solution of ammonium carbonate, can if required alsocontain dyestuds which contain tanning substances, such as haematein.

The following examples illustrate the invention:

Example 1.Silk fabricswhich have not been boiled oil" are placed on afinishing machine and drawn for example three times through a solutioncontaining the following ingredients: 5 litres of tetrachloride of tinof Baum litre of concentrated orthophosphoric acidan'd 1 litre of asolution of aluminum sulphate of 10 per cent strength.

The weighting is completed by a subsequent treatment at a temperature of60 C. with solution of water glass of 4 Baum.

Ermmple 2.-The weighting bath contains the following ingredients 6litres of solution of tetrachloride of tin of 22 Baum, 1 litre ofconcentrated formic acid, 1 litre of neutral solution of water glass of4 Baum, 120 grams of sodium phosphate, together with 100 grams of gluedissolved in 2 litres of water. V

Boiled ofi' silk after treatment in this weighting bath is pressed,drawn through a solution of ammonium carbonate of 10 per cent strength,and dried. The silk is washed in a soap bath to which haematein hasbeenadded, and then dyed.

E sample 3.-A crepe de Chine texture, consisting of natural silk isdrawn in full breadth through a 1% solution of phosphoric acidcontaining 12 gr. glue per litre. The piece is then drawn through 4 tinchloride baths containing tin tetrachloride solution of Be. The piecethen passes a squeezer and enters first a 10% mono-sodium phosphate bathand then a 6% bi-sodium phosphate bath. After the passage ofthe alkalinephosphate bath the silk goes through .a hydro-extractor and is finishedin halfan hour in a water glass solution of at least 1 B. at C. whichcontains 1 gr. soap per litre.

Example 4.Si lk skeins are dipped for a short time into a 10% solutionof mono-chloroacetic acid. One lets'the skeins drain and brings themthen into atin tetrachloride bath of 35 B. The skeins are dipped intothis metal salt bath for a shorttime, drawn out again and left in theair for a short time. This process is repeated it necessaryseveraltimes. The skeins are then carefully hydroextracted and brought for ashort time into l1? compounds containing acid compounds, and

a 1.5% mono-sodium phosphate solution. After squeezing orhydro-extraction of the liquid if desired after washing, the skeins arefinished by a short treatment in a soap containingcwater glass solutionof at least 1 B, at

Silk which is weighted in accordance withthis invention does not lose inelasticity or strength and has full brilliancy. Owing to the shorttreatment in the baths containing several weighting agents theappearance of the silk is considerably improved. The economicaladvantages of the new process are extraordinarily great, the number ofweighting baths is as far as possible reduced to a minimum, the washingand neutralization after each bath is rendered superfluous, and thetransport of the silk from one bath to another is avoided. A furtheradvantage 'consists in the fact that owing to the elimination of thewashing, acidifying and neutralization, there are not obtained dilutedsolutions of the weighting substances, or of the transformed productsproduced by the neutralization, the recovery of which substances orproducts entails considerable expense and special installations.

A further advantage of the invention is that when weighting in the pieceon the usual finishing machine, the piece can be drawn through thesolutions stretched to their full width, either singly or superimposedon each other, and in this manner the troublesome creases and spots onthe silks which often arise in consequence of the washing not havingbeen properly carried out, or other defects, are avoided.

I claim:

1. A method of weighting natural silk which comprises the steps oftreating the silk successively with solutions of acid compounds, aqueoussolutions of heavy metal compounds, and aqueous solutions ofprecipitating agents for the heavy metal compounds 3 taken up by thesilk.

2. A method of weighting natural silk which comprises the steps oftreating the silk successively with solutions of acid compounds, aqueoussolutions of heavy metal aqueous solutions of precipitating agents forthe heavy metal compounds taken up by the silk.

3. A method of weighting natural silk which comprises the steps oftreating the silk with aqueous solutions of heavy metal compounds inpresence of acid compounds and then transferring the silk directly,without washing, neutralizing or acidifying it, into 1 the followingweighting bath.

4. A method of weighting natural silk which comprises the steps .oftreating the silk with aqueous solutions of heavymetal compounds inpresence of acid compounds, squeezing it, and then transferring 1t d1-rectly, without washing, neutralizing or acidifying it, into an aqueoussolution of alkali-metal phosphate.

5. A method of weighting natural silk which comprises the steps oftreating the silk with solutions of heavy metal compounds in presence ofacid compounds and protective colloids, squeezing it andthentransferring it directly, without washing, neutralizing or acidifyingit, into an aqueous solution of alkali-metal phosphate.

6. A method of weighting naturall silk which comprises the steps oftreating the silk with solutions of tin tetrachloride in presence ofacid compounds and protective colloids, squeezing it and transferring itdirectly, without washing, neutralizing or acidifying it, into anaqueous solution of alkali-metal phosphate.

7. A method of weighting natural silk which comprises the step oftreating the silk in a single bath containing in aqueous solution aheavy metal compound, an acid compound,,and a P o -compound.

8. A method of weighting natural silk which comprises the step oftreating the silk in a single bath containing tin tetrachloride andphosphoric acid.

9. A method of weighting natural silk which comprises the step oftreating the silk in a single bath containing in aqueous solution a.heavy metal compound, an acid compound and protective colloids.

10. A method according to claim 3 in which the precipitation treatmentof the silk is followed by a treatment with an aqueous solution ofalkaline reacting substances.

11. A method according to claim 3 in which the precipitation treatmentof the silk is followed by a squeezing and a treatment with an aqueoussolution of alkaline reacting substances.

12. A method ;.according to claim 3 in which the precipitation treatmentof the silk is followed by a squeezing and a treatment with an aqueoussolution of ammonium carbonate.

13. A method of weighting natural silk which comprises the steps oftreating the silk with aqueous solutions of heavy metal compounds inpresence of organic acids, and precipitating without washing,neutralizing or acidifying the silk, the heavy metal com pounds taken upby the silk as compounds insoluble in water. 1

14. A method of weighting natural silk which comprises the' steps ofsuccessively treating the silk with an aqueous solution of tintetrachloride in presence of organic acids, and without washing,neutralizing or acidifying the silk with an aqueous solution of primarysodium phosphate.

In testimony whereof I affix my signature.

RENE OLAVEL.

